The warehouse, located in upstate New York, is a 240,000 bushel, 12-room refrigerated fruit storage facility. It has one major loading season and performs continuous storage and delivery throughout the year.

System components at the warehouse include: four 50-hp Bitzer 6F.2 open-drive reciprocating compressors mounted on a Hillphoenix rack; an Evapco water-cooled condenser; 24 Kramer and six Colmac evaporators; with two evaporators per storage room and six for the loading areas/overflow storage. The storage temperature target between 30-34°F.

The customer had five major requirements when it came to selecting a replacement refrigerant for their system’s existing R-22. The replacement refrigerant must be:

• Low GWP to mitigate regulatory and market pressures for the lifetime of the system;
• A close match in full efficiency to R-22, to maintain low energy-demand charges during the warehouse’s loading season;
• A match in temperature, pressure, and mass flow to R-22, to maintain the same equipment and piping;
• A proven match in material compatibility with R-22 components, to avoid future leaks; and
• Cost-effective.

The Retrofit Process

For this project, Daikin partnered with mechanical contractor Van Ernst Refrigeration Inc., East Rochester, New York. Daikin’s engineering team met with the customer and contractor to discuss the retrofit steps and product details and to address any final concerns prior to kick-off.

To prepare the system, the contractor began the retrofit process early with the complete replacement of mineral oil with polyolester (POE) oil. The oil was changed out over a period of two months during regular system check-ups, which included several oil changes.

The final retrofit took place over the course of four days, directly prior to the harvest season.

The system was pumped down and all R-22, a total charge of 3,200 lb., was recovered. Van Ernst’s technicians replaced all Schrader cores and caps, filter-drier cores, and other rubber seals. A deep vacuum was pulled on the system overnight, and the Creard R-407H refrigerant was added the next day.

Superheat was checked upon system startup. Evaporator distribution was found to be similar to R-22, and most of the system’s thermostatic expansion valves (TXVs) required only minor adjustments (closing). The compressor discharge pressure was higher than with R-22, and this required some adjustments to the system controller’s programming.

“Post retrofit, the system performed as the modeling suggested,” said Chris Harland, sales engineer, Van Ernst Refrigeration Inc. “With a 2-4 psi pressure rise at the evaporator and a 7-20 psi pressure rise at the compressor exit depending on outdoor ambient. Discharge temperatures fell 30-40°F, depending on outdoor ambient."

“The thing that I am happiest about was that we only had to make very small expansion valve adjustments, and coil distribution was perfect,” he added.

Harland concluded that he would like to use Creard R-407H for new projects. “I would like to use R-407H for new construction work, now that refrigerants R-404A/R-507A are getting tricky,” he said. “We have used R-407A in gas defrost condensing units up to 200,000 Btu, but getting good evaporator distribution is tougher than with R-507A, and given the GWP number of R-407A, I’d prefer to move on to R-407H for new equipment.“

Publication date: 3/7/2018

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